package org.bouncycastle.asn1.pkcs;

import java.math.BigInteger;

import org.bouncycastle.asn1.ASN1Encodable;
import org.bouncycastle.asn1.ASN1EncodableVector;
import org.bouncycastle.asn1.ASN1OctetString;
import org.bouncycastle.asn1.ASN1Sequence;
import org.bouncycastle.asn1.DERInteger;
import org.bouncycastle.asn1.DERObject;
import org.bouncycastle.asn1.DEROctetString;
import org.bouncycastle.asn1.DERSequence;
import org.bouncycastle.asn1.x509.DigestInfo;

public class MacData extends ASN1Encodable {
    private static final BigInteger ONE = BigInteger.valueOf(1);

    DigestInfo digInfo;
    byte[] salt;
    BigInteger iterationCount;

    public static MacData getInstance(Object obj) {
        if (obj instanceof MacData) {
            return (MacData) obj;
        } else if (obj instanceof ASN1Sequence) {
            return new MacData((ASN1Sequence) obj);
        }

        throw new IllegalArgumentException("unknown object in factory: "
                + obj.getClass().getName());
    }

    public MacData(ASN1Sequence seq) {
        this.digInfo = DigestInfo.getInstance(seq.getObjectAt(0));

        this.salt = ((ASN1OctetString) seq.getObjectAt(1)).getOctets();

        if (seq.size() == 3) {
            this.iterationCount = ((DERInteger) seq.getObjectAt(2)).getValue();
        } else {
            this.iterationCount = ONE;
        }
    }

    public MacData(DigestInfo digInfo, byte[] salt, int iterationCount) {
        this.digInfo = digInfo;
        this.salt = salt;
        this.iterationCount = BigInteger.valueOf(iterationCount);
    }

    public DigestInfo getMac() {
        return digInfo;
    }

    public byte[] getSalt() {
        return salt;
    }

    public BigInteger getIterationCount() {
        return iterationCount;
    }

    /**
     * <pre>
     * MacData ::= SEQUENCE {
     *     mac      DigestInfo,
     *     macSalt  OCTET STRING,
     *     iterations INTEGER DEFAULT 1
     *     -- Note: The default is for historic reasons and its use is deprecated. A
     *     -- higher value, like 1024 is recommended.
     * </pre>
     * 
     * @return the basic DERObject construction.
     */
    public DERObject toASN1Object() {
        ASN1EncodableVector v = new ASN1EncodableVector();

        v.add(digInfo);
        v.add(new DEROctetString(salt));

        if (!iterationCount.equals(ONE)) {
            v.add(new DERInteger(iterationCount));
        }

        return new DERSequence(v);
    }
}
